

Then the first-order SAV scheme (SAV1) is given by [1]}
\(\delta _t u^{n+1} & = \varepsilon ^2\Delta _h u^{n+1} - \kappa u^{n+1} + \frac{r^{n+1}}{\sqrt{E_{2h}(u^n)+\delta }}(f(u^n)+\kappa u^n), \\\delta _t r^{n+1} & = - \frac{1}{2\sqrt{E_{2h}(u^n)+\delta }} \langle f(u^n)+\kappa u^n,\delta _t u^{n+1}\rangle ,\) 
